The present invention relates to a flow sensitive valving arrangement which places a restrictive orifice in a hydraulic line when the flow in a line exceeds a selected rate. The flow sensitive valve is in a hydraulic line for an actuator which is at times under an external load tending to move the actuator. For example when a hydraulic actuator is used for controlling the lift arms of a loader, a loaded bucket may be lowered and tend to drop quickly under gravity and the restrictive orifice of the flow sensitive valve will act to limit the rate of descent of the bucket or other implement.
In some skid steer loader applications, a flow restrictor is placed into the line to the bases of the lift arm actuators, that is pressurized to lift a load. The line acts as a return line and connects the lift arm actuators to tank when the lift arms are lowered. When the bucket or other implement is loaded and heavy, the flow restrictor will permit the lift arm to lower without any consumption of independent hydraulic power, but when the lift arms and an empty bucket are lowered, which is the most common lift arm lowering condition, the pump will be required to provide fluid under pressure on the rod end of the lift arm actuator to overcome the flow restriction of the flow restrictor for retraction of the actuators to lower the lift arms. With a flow restrictor in the return line, lowering an empty bucket can take significant horsepower. This horsepower has to be provided by the engine of the machine for lowering the lift arms when there is little or no load on the lift arms.